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04256b4a8f
The sysfs_dirent serves as both an inode and a directory entry for sysfs. To prevent the sysfs inode numbers from being freed prematurely hold a reference to sysfs_dirent from the sysfs inode. [akpm@linux-foundation.org: add comment] Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com> Cc: Tejun Heo <tj@kernel.org> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
255 lines
6.3 KiB
C
255 lines
6.3 KiB
C
/*
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* fs/sysfs/inode.c - basic sysfs inode and dentry operations
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*
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* Copyright (c) 2001-3 Patrick Mochel
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* Copyright (c) 2007 SUSE Linux Products GmbH
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* Copyright (c) 2007 Tejun Heo <teheo@suse.de>
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*
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* This file is released under the GPLv2.
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*
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* Please see Documentation/filesystems/sysfs.txt for more information.
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*/
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#undef DEBUG
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#include <linux/pagemap.h>
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#include <linux/namei.h>
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#include <linux/backing-dev.h>
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#include <linux/capability.h>
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#include <linux/errno.h>
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#include <linux/sched.h>
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#include "sysfs.h"
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extern struct super_block * sysfs_sb;
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static const struct address_space_operations sysfs_aops = {
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.readpage = simple_readpage,
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.write_begin = simple_write_begin,
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.write_end = simple_write_end,
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};
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static struct backing_dev_info sysfs_backing_dev_info = {
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.ra_pages = 0, /* No readahead */
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.capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
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};
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static const struct inode_operations sysfs_inode_operations ={
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.setattr = sysfs_setattr,
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};
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int __init sysfs_inode_init(void)
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{
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return bdi_init(&sysfs_backing_dev_info);
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}
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int sysfs_setattr(struct dentry * dentry, struct iattr * iattr)
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{
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struct inode * inode = dentry->d_inode;
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struct sysfs_dirent * sd = dentry->d_fsdata;
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struct iattr * sd_iattr;
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unsigned int ia_valid = iattr->ia_valid;
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int error;
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if (!sd)
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return -EINVAL;
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sd_iattr = sd->s_iattr;
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error = inode_change_ok(inode, iattr);
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if (error)
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return error;
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iattr->ia_valid &= ~ATTR_SIZE; /* ignore size changes */
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error = inode_setattr(inode, iattr);
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if (error)
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return error;
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if (!sd_iattr) {
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/* setting attributes for the first time, allocate now */
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sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
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if (!sd_iattr)
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return -ENOMEM;
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/* assign default attributes */
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sd_iattr->ia_mode = sd->s_mode;
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sd_iattr->ia_uid = 0;
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sd_iattr->ia_gid = 0;
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sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME;
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sd->s_iattr = sd_iattr;
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}
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/* attributes were changed atleast once in past */
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if (ia_valid & ATTR_UID)
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sd_iattr->ia_uid = iattr->ia_uid;
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if (ia_valid & ATTR_GID)
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sd_iattr->ia_gid = iattr->ia_gid;
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if (ia_valid & ATTR_ATIME)
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sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime,
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inode->i_sb->s_time_gran);
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if (ia_valid & ATTR_MTIME)
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sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
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inode->i_sb->s_time_gran);
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if (ia_valid & ATTR_CTIME)
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sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
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inode->i_sb->s_time_gran);
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if (ia_valid & ATTR_MODE) {
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umode_t mode = iattr->ia_mode;
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if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
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mode &= ~S_ISGID;
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sd_iattr->ia_mode = sd->s_mode = mode;
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}
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return error;
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}
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static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
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{
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inode->i_mode = mode;
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inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
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}
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static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
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{
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inode->i_mode = iattr->ia_mode;
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inode->i_uid = iattr->ia_uid;
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inode->i_gid = iattr->ia_gid;
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inode->i_atime = iattr->ia_atime;
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inode->i_mtime = iattr->ia_mtime;
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inode->i_ctime = iattr->ia_ctime;
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}
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/*
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* sysfs has a different i_mutex lock order behavior for i_mutex than other
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* filesystems; sysfs i_mutex is called in many places with subsystem locks
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* held. At the same time, many of the VFS locking rules do not apply to
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* sysfs at all (cross directory rename for example). To untangle this mess
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* (which gives false positives in lockdep), we're giving sysfs inodes their
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* own class for i_mutex.
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*/
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static struct lock_class_key sysfs_inode_imutex_key;
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static int sysfs_count_nlink(struct sysfs_dirent *sd)
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{
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struct sysfs_dirent *child;
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int nr = 0;
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for (child = sd->s_dir.children; child; child = child->s_sibling)
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if (sysfs_type(child) == SYSFS_DIR)
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nr++;
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return nr + 2;
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}
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static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
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{
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struct bin_attribute *bin_attr;
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inode->i_private = sysfs_get(sd);
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inode->i_mapping->a_ops = &sysfs_aops;
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inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
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inode->i_op = &sysfs_inode_operations;
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inode->i_ino = sd->s_ino;
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lockdep_set_class(&inode->i_mutex, &sysfs_inode_imutex_key);
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if (sd->s_iattr) {
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/* sysfs_dirent has non-default attributes
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* get them for the new inode from persistent copy
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* in sysfs_dirent
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*/
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set_inode_attr(inode, sd->s_iattr);
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} else
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set_default_inode_attr(inode, sd->s_mode);
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/* initialize inode according to type */
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switch (sysfs_type(sd)) {
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case SYSFS_DIR:
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inode->i_op = &sysfs_dir_inode_operations;
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inode->i_fop = &sysfs_dir_operations;
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inode->i_nlink = sysfs_count_nlink(sd);
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break;
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case SYSFS_KOBJ_ATTR:
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inode->i_size = PAGE_SIZE;
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inode->i_fop = &sysfs_file_operations;
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break;
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case SYSFS_KOBJ_BIN_ATTR:
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bin_attr = sd->s_bin_attr.bin_attr;
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inode->i_size = bin_attr->size;
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inode->i_fop = &bin_fops;
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break;
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case SYSFS_KOBJ_LINK:
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inode->i_op = &sysfs_symlink_inode_operations;
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break;
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default:
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BUG();
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}
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unlock_new_inode(inode);
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}
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/**
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* sysfs_get_inode - get inode for sysfs_dirent
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* @sd: sysfs_dirent to allocate inode for
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*
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* Get inode for @sd. If such inode doesn't exist, a new inode
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* is allocated and basics are initialized. New inode is
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* returned locked.
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*
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* LOCKING:
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* Kernel thread context (may sleep).
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*
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* RETURNS:
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* Pointer to allocated inode on success, NULL on failure.
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*/
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struct inode * sysfs_get_inode(struct sysfs_dirent *sd)
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{
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struct inode *inode;
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inode = iget_locked(sysfs_sb, sd->s_ino);
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if (inode && (inode->i_state & I_NEW))
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sysfs_init_inode(sd, inode);
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return inode;
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}
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/*
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* The sysfs_dirent serves as both an inode and a directory entry for sysfs.
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* To prevent the sysfs inode numbers from being freed prematurely we take a
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* reference to sysfs_dirent from the sysfs inode. A
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* super_operations.delete_inode() implementation is needed to drop that
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* reference upon inode destruction.
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*/
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void sysfs_delete_inode(struct inode *inode)
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{
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struct sysfs_dirent *sd = inode->i_private;
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truncate_inode_pages(&inode->i_data, 0);
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clear_inode(inode);
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sysfs_put(sd);
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}
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int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name)
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{
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struct sysfs_addrm_cxt acxt;
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struct sysfs_dirent *sd;
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if (!dir_sd)
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return -ENOENT;
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sysfs_addrm_start(&acxt, dir_sd);
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sd = sysfs_find_dirent(dir_sd, name);
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if (sd)
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sysfs_remove_one(&acxt, sd);
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sysfs_addrm_finish(&acxt);
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if (sd)
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return 0;
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else
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return -ENOENT;
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}
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